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Recent advances in technology have made desalination of seawater and groundwater a realistic option for increasing water supplies in some parts of the United States, and desalination will likely have a niche in the nation's future water management portfolio. However, its potential is constrained by a host of financial, social, and environmental factors. Substantial uncertainties remain about the environmental impacts of desalination, which have led to costly permitting delays. The National Research Council, with the support of the U.S. Bureau of Reclamation and the U.S. Environmental Protection Agency, convened a committee to assess the state-of-the-art in desalination technologies, identify implementation challenges, and provide recommendations for action and research. The report concludes that a coordinated, strategic research effort with steady funding is needed to better understand and minimize desalination's environmental impacts - and to find ways to further lower its costs and energy use.

Key Messages

Conservation and transfers from low- to high-valued uses will usually be less costly than supply augmentation schemes, including desalination.

For brackish water desalination, the costs of concentrate management can vary enormously from project to project and may rival energy and capital costs as the largest single component of cost.

Possible environmental impacts of desalination are impingement and entrainment of organisms when seawater is taken in, ecological impacts from disposing of salt concentrates, and increased greenhouse gas emissions from increased energy use, among other concerns. Although limited studies to date suggest that the environmental impacts may be less detrimental than many other types of water supply, site-specific information necessary to make detailed conclusions on environmental impacts is typically lacking.

Substantial reductions in the financial cost of producing desalinated water will require substantial reductions in either energy costs or capital costs

The costs of producing desalinated water the cost of removing salts to create freshwater is no longer the primary barrier to implementing desalination technology, because there have been significant reductions in desalination production costs.

The potential for desalination cannot be definitively determined because it depends on a host of complicated and locally variable economic, social, environmental, and political factors. In the complete absence of these factors, the theoretical potential for desalination is effectively unlimited.

The private sector appears to fund the majority of desalination research, with total annual spending estimated to be more than twice that of all other surveyed sources of such funding.

There are small but significant efficiencies that can be made in membrane technologies that will reduce the energy needed to desalinate water and, therefore, offer potentially important process cost reductions.

There is no integrated and strategic direction to the federal desalination research and development efforts.